public class Example4_20 {
    public static void main(String args[]) {
      char a[] = {'a','b','c','D','E','F'};
      for(int i=0;i<a.length;i++) {
	if(Character.isLowerCase(a[i])) 
	  a[i]=Character.toUpperCase(a[i]);
	else if(Character.isUpperCase(a[i]))
	  a[i]=Character.toLowerCase(a[i]);
      }
      for(int i=0;i<a.length;i++) 
      System.out.print(" "+a[i]);
    }
}
